A conventional printer includes a carriage for holding a print cartridge containing ink. The carriage is typically scanned across the width of a media and ink is ejected from the print cartridge in a controlled manner to form a swath of an image during each scan. The height of the printed swath (as measured in the direction the media is advanced) is fixed for a particular printhead.
Between carriage scans, the media is advanced so that the next swath of the image may be printed. In most cases, the base of the just-printed swath must be precisely aligned with the top of the next-printed swath so that a continuous image may be printed on the media. Alternatively, the media may be advanced by less than a full swath height to effect a “shingling” type of printing. In any event, inaccurate media advances between carriage scans often result in print quality artifacts known as banding.
In an effort to prevent errors such as banding, conventional printers often employ techniques for determining offsets in the advancement of the media. Conventional printers also employ various correction techniques in an attempt to compensate for the offsets. The techniques employed by conventional printers, however, typically fail to adequately compensate for the offsets and are often difficult to implement.